Nitric Oxide-Releasing Xerogel-Based Fiber-Optic pH Sensors

A xerogel-based optical pH sensor capable of releasing low levels of nitric oxide (NO) and measuring changes in solution pH is reported. Through simple dip-coating procedures, aminoalkoxysilane-based xerogel films modified with N-diazeniumdiolate NO donor precursors and the fluorescent pH indicator seminaphthorhodamine-1 carboxylate (SNARF-1) were sequentially deposited onto optical fibers. The resulting sensors were characterized by fast and linear response to pH throughout the physiological range (pH 7.0-7.8). Real-time chemiluminescence measurements confirmed the presence of the overlying SNARF-1 containing TMOS layer did not have an inhibitory effect on N-diazeniumdiolate formation or NO release, and the NO-releasing coatings were capable of maintaining NO fluxes >0.4 pmol/cm2s up to 16 h. In vitro blood compatibility studies using porcine platelets confirmed the expected thromboresistivity of the NO-releasing xerogel coatings

Reduced bacterial adhesion to fibrinogen-coated substrates via nitric oxide release

The ability of nitric oxide (NO)-releasing xerogels to reduce fibrinogen-mediated adhesion of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli is described. A negative correlation was observed between NO surface flux and bacterial adhesion for each species tested. For S. aureus and E. coli, reduced adhesion correlated directly with NO flux from 0 to 30 pmol cm−2 s−1. A similar dependence for S. epidermidis was evident from 18 to 30 pmol cm−2 s−1. At a NO flux of 30 pmol cm−2 s−1, surface coverage of S. aureus, S. epidermidis, and E. coli was reduced by 96, 48, and 88%, respectively, compared to non-NO-releasing controls. Polymeric NO release was thus demonstrated to be an effective approach for significantly reducing fibrinogen-mediated adhesion of both gram-positive and gram-negative bacteria in vitro, thereby illustrating the advantage of active NO release as a strategy for inhibiting bacterial adhesion in the presence of pre-adsorbed protein

Inflammatory Leiomyosarcoma and Histiocyte-rich Rhabdomyoblastic Tumor : a clinicopathological, immunohistochemical and genetic study of 13 cases, with a proposal for reclassification as Inflammatory Rhabdomyoblastic Tumor

Inflammatory leiomyosarcoma (ILMS), defined as a malignant neoplasm showing smooth muscle differentiation, a prominent inflammatory infiltrate, and near-haploidization , is a very rare soft tissue tumor with a generally favorable prognosis. The morphologic features of histiocyte-rich rhabdomyoblastic tumor (HRRMT) are similar to those of ILMS, although this lesion shows by definition a skeletal muscle phenotype. Recent gene expression profiling and immunohistochemical studies have also suggested that ILMS and HRRMT may be related. We studied the clinicopathologic, immunohistochemical and genetic features of four cases previously classified as ILMS and nine classified as HRRMT. Tumors from both groups tended to occur in the deep soft tissues of the extremities of young to middle-aged males and exhibited indolent behavior. Morphologically, all were well-circumscribed, often encapsulated, and showed a striking histiocyte-rich inflammatory infiltrate admixed with variably pleomorphic tumor cells showing spindled and epithelioid to rhabdoid morphology, eosinophilic cytoplasm, and prominent nucleoli, but few, if any, mitotic figures. Immunohistochemically, the tumor cells expressed desmin, alpha-smooth muscle actin, and the rhabdomyoblastic markers PAX7, MyoD1, and myogenin. H-caldesmon expression was absent in all cases, using the specific h-CD antibody. Karyotypic study (1 HRRMT) and genome-wide copy number analysis (7 HRRMT, OncoScan SNP assay), revealed near-haploidization in four cases, with subsequent genome doubling in one, an identical phenotype to that seen in ILMS. We propose reclassification of ILMS and HRRMT as inflammatory rhabdomyoblastic tumor , a name which accurately describes the salient morphologic and immunohistochemical features of this distinctive tumor, as well as its intermediate (rarely metastasizing) clinical behavior

Stem cell ageing and non-random chromosome segregation

Adult stem cells maintain the mature tissues of metazoans. They do so by reproducing in such a way that their progeny either differentiate, and thus contribute functionally to a tissue, or remain uncommitted and replenish the stem cell pool. Because ageing manifests as a general decline in tissue function, diminished stem cell-mediated tissue maintenance may contribute to age-related pathologies. Accordingly, the mechanisms by which stem cell regenerative potential is sustained, and the extent to which these mechanisms fail with age, are fundamental determinants of tissue ageing. Here, we explore the mechanisms of asymmetric division that account for the sustained fitness of adult stem cells and the tissues that comprise them. In particular, we summarize the theory and experimental evidence underlying non-random chromosome segregation—a mitotic asymmetry arising from the unequal partitioning of chromosomes according to the age of their template DNA strands. Additionally, we consider the possible consequences of non-random chromosome segregation, especially as they relate to both replicative and chronological ageing in stem cells. While biased segregation of chromosomes may sustain stem cell replicative potential by compartmentalizing the errors derived from DNA synthesis, it might also contribute to the accrual of replication-independent DNA damage in stem cells and thus hasten chronological ageing

Resolution of Crizotinib-Associated Fulminant Hepatitis following Cessation of Treatment

Targeted cancer treatments offer the prospect of precise inhibition of tumor growth without the untoward off-target toxicity of traditional chemotherapies. Still, unintended, often idiosyncratic side effects, such as drug-induced liver injury, can occur. We discuss the case of a 26-year-old female with a history of ROS1-rearranged lung adenocarcinoma, undergoing treatment with the tyrosine kinase inhibitor crizotinib, who presented to our hospital with abdominal pain and scleral icterus. Liver chemistries were notable for hyperbilirubinemia (5 mg/dL total) and marked transaminasemia (AST 1736 U/L, ALT >3500 U/L); liver biopsy demonstrated acute hepatitis with extensive necrosis. There was no evidence of an infectious or autoimmune etiology. It was discovered that the patient was taking a 500 mg once daily dose of crizotinib, in lieu of the intended dose of 250 mg twice daily. After immediate cessation of crizotinib therapy upon hospital admission, there was complete biochemical resolution of the hepatitis. This case highlights the potential reversibility of fulminant crizotinib-associated hepatoxicity, possibly related to supratherapeutic dosing, when managed with abrupt stoppage of the drug and initiation of supportive care

The Majority of Patients Who Undergo ERCP When Large Duct Obstruction Is Evident on Liver Biopsy Have Biliary Findings Amenable to Endoscopic Intervention

(1) Background: Abnormal liver function tests are commonly encountered in clinical practice, often leading to additional workup to determine the underlying etiology of these abnormal laboratory studies. As part of this evaluation, if less invasive imaging studies are performed and are without evidence of biliary obstruction, liver biopsy may be performed, and the finding of large duct obstruction on liver biopsy is commonly encountered. The utility of endoscopic retrograde cholangiopancreatography (ERCP) for evaluation and management of possible biliary obstruction in patients with large duct obstruction on liver biopsy has not been studied to date. (2) Methods: To assess the utility of ERCP in patients with large bile duct obstruction on liver biopsy, we retrospectively evaluated patients with large duct obstruction on liver biopsy from 2010–2019 at our tertiary care and transplant center. Demographic and clinical characteristics were evaluated for all patients, with sub-group analysis for patients who underwent ERCP and those who had intervenable findings at the time of ERCP. Descriptive statistics with proportions, means, and standard deviations were performed for demographics and clinical variables using absolute standardized difference. (3) Results: During the study period, 189 liver biopsies with evidence of large duct obstruction were performed. After exclusion criteria were applied, 166 unique patients were eligible for the study. Ninety-one patients with evidence of large duct obstruction on liver biopsy underwent ERCP and 75 did not. Of the 91 patients who underwent ERCP, 76 patients (84%) had an intervenable finding at ERCP. Patients who underwent ERCP were overall more likely to have had a liver transplant (65% ASD 0.63), have previously undergone cholecystectomy (80%, ASD 0.56), and be immunocompromised (80%, ASD 0.56). (4) Conclusions: ERCP is high yield when large duct obstruction is apparent on liver biopsy, with the majority of patients (84%) who undergo ERCP in this clinical context having a biliary finding necessitating therapeutic endoscopic intervention

Endoscopic Resection of Skull Base Teratoma in Klippel-Feil Syndrome through Use of Combined Ultrasonic and Bipolar Diathermy Platforms

Klippel-Feil syndrome (KFS) is associated with numerous craniofacial abnormalities but rarely with skull base tumor formation. We report an unusual and dramatic case of a symptomatic, mature skull base teratoma in an adult patient with KFS, with extension through the basisphenoid to obstruct the nasopharynx. This benign lesion was associated with midline palatal and cerebral defects, most notably pituitary and vertebrobasilar arteriolar duplications. A multidisciplinary workup and a complete endoscopic, transnasal surgical approach between otolaryngology and neurosurgery were undertaken. Out of concern for vascular control of the fibrofatty dense tumor stalk at the skull base and need for complete teratoma resection, we successfully employed a tissue resection tool with combined ultrasonic and bipolar diathermy to the tumor pedicle at the sphenoid/clivus junction. No CSF leak or major hemorrhage was noted using this endonasal approach, and no concerning postoperative sequelae were encountered. The patient continues to do well now 3 years after tumor extirpation, with resolution of all preoperative symptoms and absence of teratoma recurrence. KFS, teratoma biology, endocrine gland duplication, and the complex considerations required for successfully addressing this type of advanced skull base pathology are all reviewed herein

Ex Vivo Expansion and In Vivo Self-Renewal of Human Muscle Stem Cells

Adult skeletal muscle stem cells, or satellite cells (SCs), regenerate functional muscle following transplantation into injured or diseased tissue. To gain insight into human SC (huSC) biology, we analyzed transcriptome dynamics by RNA sequencing of prospectively isolated quiescent and activated huSCs. This analysis indicated that huSCs differentiate and lose proliferative potential when maintained in high-mitogen conditions ex vivo. Further analysis of gene expression revealed that p38 MAPK acts in a transcriptional network underlying huSC self-renewal. Activation of p38 signaling correlated with huSC differentiation, while inhibition of p38 reversibly prevented differentiation, enabling expansion of huSCs. When transplanted, expanded huSCs differentiated to generate chimeric muscle and engrafted as SCs in the sublaminar niche with a greater frequency than freshly isolated cells or cells cultured without p38 inhibition. These studies indicate characteristics of the huSC transcriptome that promote expansion ex vivo to allow enhanced functional engraftment of a defined population of self-renewing huSCs

Chromatin Modifications as determinants of muscle stem cell quiescence and chronological aging

The ability to maintain quiescence is critical for the long-term maintenance of a functional stem cell pool. To date, the epigenetic and transcriptional characteristics of quiescent stem cells and how they change with age remain largely unknown. In this study, we explore the chromatin features of adult skeletal muscle stem cells, or satellite cells (SCs), which reside predominantly in a quiescent state in fully developed limb muscles of both young and aged mice. Using a ChIP-seq approach to obtain global epigenetic profiles of quiescent SCs (QSCs), we show that QSCs possess a permissive chromatin state in which few genes are epigenetically repressed by Polycomb group (PcG)-mediated histone 3 lysine 27 trimethylation (H3K27me3), and a large number of genes encoding regulators that specify nonmyogenic lineages are demarcated by bivalent domains at their transcription start sites (TSSs). By comparing epigenetic profiles of QSCs from young and old mice, we also provide direct evidence that, with age, epigenetic changes accumulate and may lead to a functional decline in quiescent stem cells. These findings highlight the importance of chromatin mapping in understanding unique features of stem cell identity and stem cell aging